Comparison of sleep and other non-motor symptoms between SWEDDs patients and de novo Parkinson's disease patients

SWEDDs (Scans Without Evidence of Dopaminergic Deficits) was defined from a series of pharmaceutical trials on Parkinson's disease (PD). Non-motor features including sleep-related problems are common even in early-stage PD patients; however, little is known about the burden of the non-motor symptoms in SWEDDs patients. Methods: The Non-motor Symptoms Assessment Scale (NMSS), revised version of the Parkinson's Disease Sleep Scale (PDSS-2), Epworth Sleepiness Scale (ESS), and EuroQol 5-Dimension (EQ-5D) were applied to evaluate 17 SWEDDs patients and 28 de novo PD patients. The presence of clinically probable rapid eye movement sleep behavior disorder (cpRBD) was assessed using the International Classification of Sleep Disorders-Revised (ICSD-R) criteria. Results: The total NMSS score for the SWEDDs group was significantly lower than for the de novo PD group (p=0.032). The most distinct difference was in taste or smell change (p<0.000). Prevalence of cpRBD was higher in de novo PD patients than in SWEDDs patients (p=0.030), though no significant differences in the PDSS-2 total score (p=0.496) or the ESS score (p=0.517) were found. The SWEDDs patients did not significantly differ from the de novo PD patients with regard to quality of life, as measured by the EQ-5D index score (p=0.177). Conclusions: The patients with SWEDDs have less non-motor problems than newly diagnosed untreated PD patients. Given the difficulty distinguishing between SWEDDs and early PD, identifying some of non-motor symptoms, such as RBD or olfactory impairment, could aid clinicians in their work.